Guys you like but barely know?

so what do you do about a guy you think you'd hit it off with but barely know?

there's this guy i used to work with and i think we'd be really good together, but i dont know him well enough to say whether i like him or not... i guess i think i'd like him... we don't work together anymore, we've never really talked much or hung out, and we aren't in the same major so we have none of the same classes...

what do you do in a situation like that? im trying not to be super stalkerish by going way out of my way to talk to him